The invention relates to flexible shaft couplings of the tubularly-shaped, yielding element type, but more particularly, the invention relates to a sporadical torque transferring device that enhances performance of a tubularly-shaped, yielding type flexible shaft coupling.
Some yielding element type flexible shaft couplings are useful for attenuating certain noise and vibration in some rotary, articulated shaft systems. Examples of such flexible elements appear in U.S. Pat. Nos. 3,628,352; 3,855,817; 3,347,061; and 3,621,674. Apparatus for attaching such yielding element couplings to rotary shafting are shown in U.S. Pat. Nos. 3,788,098; and 3,973,411. An example of a torque overload device for tubularly-shaped yielding element couplings appears in U.S. patent application Ser. No. 34,069. While such couplings are suitable for attenuating noise and vibration, the couplings are susceptible to buckling failure at infrequent torque overloads. The torque overload device of the above referenced application solves many of the infrequent torque overload problems; however, such torque overload devices may possibly disengage when used with flexible element couplings having a torsional spring rate less than about 100 foot pounds per degree. Another drawback to such overload devices is that they may not accommodate some of the interconnecting articulated shaft length building tolerances which occur in some applications such as half shafts for use with automobile front wheel drives.